Certain types of automotive suspension systems, such as the MacPherson-type, include a suspension subassembly. The subassembly includes a shock absorber and a spring, and is often referred to as a strut assembly. The shock absorber or damper consists of a piston within the body of the shock absorber connected to a piston rod which projects upwardly from the shock absorber in a telescoping fashion. A coil spring is mounted in a compressed states around the piston rod and body of the shock absorber between a lower spring seat integral with the body of the absorber and an upper spring seat fastened to the upper end of the piston rod of the shock absorber. Such a suspension subassembly is mounted as a unit in the vehicle body and is disassembled, serviced, and reassembled separately.
Disassembly of the strut assembly is accomplished by compressing the coil spring using a suitable tool to remove pressure from the lower spring seat of the strut assembly. Having done so, the retaining means-holding the piston rod to the upper spring seat can be removed. This retaining means variously takes the form of a nut or retaining ring which fastens above the upper spring seat to the piston rod retaining all components of the strut assembly. The shock absorber and lower spring seat can then be removed leaving the spring in a compressed state within the tool. If required, the spring can then be decompressed and removed. In some cases, the coil spring must be compressed by engaging the spring between the upper and lower spring seats rather than engaging the upper spring seat and spring.
New or serviced components can be assembled following the reverse of the foregoing process. Namely, with the spring in a compressed state, the shock absorber is placed axially through the spring such that the piston rod protrudes beyond the coil spring upper end and the lower spring seat contacts the lower end of the compressed spring. The appropriate retaining means is fastened to the piston rod above the upper spring seat. The strut assembly is released from the tool and is ready for reinstallation in the vehicle.
Numerous apparatus have been developed to assist in the assembly and disassembly of a strut suspension system. Examples of these may be found in U.S. Pat. Nos. 4,558,500; 4,520,543; 4,516,303; 4,494,289; 4,785,519; 5,031,294; and 5,680,686 to name a few. With the design and development of newer and different types of strut assemblies, it has become desirable to have an apparatus which can accept a wide variety of different types of strut assemblies and different types and sizes of MacPherson strut assemblies. It is also desirable that the apparatus is able to be quickly adapted by the user to accept a particular sized strut assembly for quick and efficient assembling and disassembling. It is also recognized to be important to ensure that the apparatus can securely engage and retain a spring to be compressed and otherwise ensure safety to an operator since the springs are compressed under a large force which, if released without control, could injure an operator.